1. Field of the Invention
The present invention relates to a circuit board connector to be provided on a circuit board.
2. Description of the Related Art
Generally, a circuit board connector has a housing fixed to a circuit board, which accommodates terminals. A board connecting pin formed on each of the terminals is projected from a bottom opening portion of the housing to the outside. Further, each of the board connecting pins is inserted into a corresponding mounting hole formed in the circuitboard. Then, an inserted part of each of the board connecting pints is soldered thereto. Thus, the circuit board connector is electrically connected to the circuit board.
Meanwhile, when the board connector is mounted on the circuit board, a leading end of the board connecting pin may interfere with and be caught on the inner peripheral surface of the mounting hole of the circuit board. Further, after the board connecting pins are soldered thereto, fitting resistance to the terminal of the board connector is sometimes caused owing to a board connecting portion of the counterpart connector of the board connector, so that the terminal is slightly moved. Thus, to eliminate such inconvenience, a V-bent elastic flexible portion is formed on each of the board connecting pins. Elastic deformation of this flexible portion serves to prevent excessive stress from being exerted on the board connecting pins, and to prevent solder cracks from occurring therein.
However, because of the elongated shape of each of the board connecting pins, it is difficult to bend and form the elastic flexible portion with high accuracy. Thus, when the board connector is set on the circuitboard, misalignment between the board connecting pin and the corresponding mounting hole occurs. Therefore, to eliminate such inconvenience, a retainer for positioning the board connecting pins at regular positions thereof is attached to the housing. Moreover, the board connector is mounted on the circuit board after the retainer is attached to the housing and the alignment of the board connecting pins is adjusted.
However, generally, materials forming the housing and the retainer are PBT (polybutylene terephthalate) and largely differ in coefficient of thermal expansion from the circuit board made of a glass epoxy resin. Therefore, this conventional board connector has a drawback in that displacement of the board connecting pin is easy to occur when the housing, the retainer, and the circuit board respectively expand and contract by different amounts owing to heat generated in the external environment and components mounted on a junction block.
Thus, it has been considered that the housing and the retainer are made of a material whose coefficients of thermal expansion are close to that of the material of the circuit board. To put it concretely, such a material is PBT to which glass is mixed (that is, PBT-G). However, when this material is employed, the aforementioned inconvenience is solved, while there is caused another drawback in that the connecting portion between the retainer and the housing is easy to break because both materials of the housing and the retainer are hard.
The present invention is accomplished in view of the aforementioned drawbacks, and therefore an object of the invention is to provide a board connector that can secure the function of adjusting the alignment of the board connecting portion and that enables the assembly of the housing and the retainer without causing damage thereto.
To achieve the foregoing object, according to a first aspect of the invention, there is provided a connector for a circuit board, which has terminals accommodated in a housing to be fixed to a circuit board, and board connecting portions each including an elastic flexible portion formed on each of the terminals. A leading end portion of each of the board connecting portions, which is projected from the housing, is fixed to the circuit board. This connector comprises a retainer attached to a side face, from which a corresponding one of the board connecting portions is projected, of the housing. A first adjusting portion for adjusting alignment of the board connecting portion in a predetermined direction is provided in the housing. A second adjusting portion for adjusting alignment of the board connecting portions in a direction orthogonal to the predetermined direction is provided in the retainer.
According to a second aspect of the invention, in the connector according to the first aspect of the invention, one of the housing and the retainer is mounted on the circuit board by being in contact therewith, and made of a material whose coefficient of thermal expansion is nearly equal to that of thermal expansion of a material of the circuit board.
According to a third aspect of the invention, in the connector according to the first aspect of the invention, one of the first adjusting portion and the second adjusting portion is used for adjusting alignment of the board connecting portion in a longitudinal direction of a connector body. Moreover, the one of the housing and the retainer is made of a material whose coefficient of thermal expansion is nearly equal to that of thermal expansion of a material of the circuit board.
According to a fourth aspect of the invention, in the connector according to any one of the first to third aspects of the invention, the second adjusting portion is a slit extending in a longitudinal direction of the retainer.
According to a fifth aspect of the invention, in the connector according to any one of the first to fourth aspects of the invention, the first adjusting portion is an engaging groove with which both side parts of the elastic flexible portion are engaged in a state in which both the side parts abut against the engaging groove.
According to the first aspect of the invention, the alignment of the board connecting portions is adjusted in a predetermined direction by the first adjusting portion. Moreover, the alignment of the board connecting portions in a direction orthogonal to the predetermined direction is adjusted by the second adjusting portion. In short, the board connecting portions can be positioned at regular positions by both the adjusting portions. Therefore, even when one of the housing and the retainer employs a soft material, that is, a material differing in coefficient of thermal expansion from the circuit board, it is sufficient to adjust only the alignment in a direction in which the expansion or contraction of the circuit board is small. Thus, the housing and the retainer can be incorporated thereinto without being damaged, while the function of adjusting the alignment of the board connecting portions is secured.
According to the second aspect of the invention, one of the housing and the retainer, which are in contact with the circuit board, is formed from a material whose coefficient of thermal expansion is nearly equal to that of thermal expansion of the material of the circuit board. Thus, the displacement of the board connecting portions can be prevented from being caused as the housing, the retainer, and the circuitboard expand and contract by different amounts, respectively. Consequently, an occurrence of semiconductor cracks can be reliably prevented.
According to the third aspect of the invention, one of the housing and the retainer, which are used for adjusting the alignment of the board connecting portions in the longitudinal direction of the connector body, is formed from a material whose coefficient of thermal expansion is nearly equal to that of thermal expansion of the circuit board. This results in reduction in an amount, by which the housing or the retainer expands and contracts in the longitudinal direction of the connector body owing to heat generated in the external environment and generated by components mounted on a junction block.
According to the fourth aspect of the invention, the second adjusting portion is a slit extending in the longitudinal direction of the retainer. Thus, the board connecting portions can easily be inserted into the slit. Consequently, the retainer can easily be attached to the housing.
According to the fifth aspect of the invention, the first adjusting portion is an engaging groove with which an elastic flexible portion is engaged. Thus, although the first adjusting portion has a simple shape, the first adjusting portion can reliably prevent the displacement of the board connecting portions.